BAGHDAD — A barrage of car bomb and suicide bomb blasts rocked Baghdad and two northern Iraqi communities Thursday, killing at least 61 people during a major holiday period and extending a relentless wave of bloodshed gripping the country.

The bulk of the blasts struck in mainly Shiite Muslim parts of the Iraqi capital shortly after nightfall, sending ambulances racing through the streets with sirens blaring. Authorities reported nine car bomb explosions across Baghdad, including one near a playground that killed two children.

It was the deadliest day in Iraq since Oct. 5, when a suicide bombing targeting Shiite pilgrims and other attacks left at least 75 dead.

Iraq is weathering its deadliest outburst of violence since 2008, raising fears the country is returning to the widespread sectarian killing that pushed it to the brink of civil war in the years after the 2003 U.S.-led invasion. Iraq’s resurgent branch of al-Qaida is believed to be behind much of the killing as part of its campaign to undermine the Shiite-led government.

Thursday’s bloodshed began early in the morning when a suicide bomber blew up his explosives-laden car among houses in an ethnic minority village in northern Iraq. That attack, in the Shabak village of al-Mouafaqiyah near the restive city of Mosul, 360 kilometers (225 miles) northwest of Baghdad, killed at least 15 and wounded 52, police said.

The United Nations envoy to Iraq condemned the attack and said rising violence in Ninevah province requires “urgent action and strengthened security cooperation” between regional authorities and the central government.

The town, a frequent flashpoint for violence, sits in a band of territory contested by Arabs, Kurds and Turkomen about 200 kilometers (130 miles) north of Baghdad.

The attacks struck as Muslims around the world this week mark the religious holiday of Eid al-Adha, or the Feast of Sacrifice. The holiday marks the willingness of the prophet Ibrahim — or Abraham, as he is known in the Bible — to sacrifice his son in accordance with God’s will, and is often a time for family celebrations and outings.

The Baghdad explosions went off in quick succession after sunset as families were heading out to parks, coffee shops and restaurants, police said.

Back-to-back car bombs exploded about two blocks apart in the mainly Shiite neighborhood of Husseiniyah, killing a total of 11 and wounding 22, authorities said.

Other mainly Shiite neighborhoods hit were the southeastern New Baghdad, where four died and 12 were wounded, and the eastern Sadr City, where a car bomb near a playground killed five, including two children, and wounded 16, officials said. Another car bomb exploded near a restaurant in the northeastern Shiite neighborhood of Gareat, killing seven and wounding 14, authorities said.

Elsewhere, a suicide bomber drove a car packed with explosives into a police checkpoint in the southern district of Dora, killing five people, including three police officers, and wounding nine, authorities said.

Two parked car bombs exploded near an outdoor market and shops in the mixed Shiite and Christian neighborhood of Garage al-Amana, killing eight and wounding 15, officials said.

The predominantly Sunni neighborhood of Shurta also was hit, with three killed and 12 wounded when a car bomb exploded in a commercial street, authorities said.

Hospital officials confirmed the casualties. Officials spoke on condition of anonymity because they weren’t authorized to release the information.

There was no immediate claim of responsibility for Thursday’s blasts, though suicide bombings and car bombings are a favorite tactic of Al-Qaida’s local branch. It frequently targets Shiites, whom it considers heretics, and those seen as closely allied to the Shiite-led government in Baghdad.

Violence has escalated sharply since late April following a deadly crackdown by security forces on a camp for Sunni protesters in the northern town of Hawija.

The U.N. reported 979 people killed violently in Iraq last month. At least 350 more have died in attacks in Iraq so far this month, according to an Associated Press count.